Routine endometrial biopsy is commonly performed using a flexible 3-mm catheter with rounded distal end having a side-hole for curettage and collection of tissue. Such catheters typically contain a flexible internal plunger that seals with the internal surface of the catheter. When the internal plunger is pulled back, suction is created. The suction is used to obtain endometrial tissue as the catheter is passed back and forth with rotation within the uterine cavity while the distal side hole scrapes tissue from the internal walls of the cavity. See, e.g., Zinnanti U.S. Pat. No. 5,069,224, Fowler U.S. Pat. No. 5,807,282, and Cornier U.S. Pat. No. 6,042,552.
The use of a flexible catheter follows the natural contours of the uterine cavity, which is an advantage to patient care, causing less pain and tissue trauma compared to needle or ridged-cannula biopsy devices. However, the process of transferring the sample from the catheter to a specimen container is inherently difficult with such typical biopsy devices because the flexible plunger must be reintroduced into the flexible catheter to expel the contents. This process is slow and technically difficult, and may result in loss of the sample, leading to the need for a second procedure.
Additionally, the limited volume of such typical endometrial catheters frequently does not create enough suction to obtain an adequate sample, and multiple passes with the same catheter, consisting of multiple iterations of obtaining and expelling a sample, must be performed. This process is further complicated by the need to prevent the sterile catheter tip from touching a non-sterile specimen container in order to prevent contamination when multiple passes are required.
Thus, although such prior-art devices can be simple to use and manufacture, each suffers from the disadvantages of a limited amount of suction and the need to force a long, flexible plunger back into the device in order to retrieve the specimen. These disadvantages result in loss of time and increased patient discomfort because the catheter must be reintroduced multiple times to retrieve an adequate sample and because the difficulty of replacing the plunger to retrieve the sample frequently leads to loss of sample, thus requiring a second procedure.
A few endometrial tissue collection systems employ the use of a syringe. The syringe has the advantage of creating more suction for aspiration so that an adequate sample is obtained each time; however, in currently available products, the plunger must be manually withdrawn from the syringe barrel to create suction. This action of pulling on the syringe plunger at the same time the catheter is inserted into the uterine cavity is inherently dangerous and may cause inadvertent harm or uterine perforation as the catheter is being pushed forward toward the patient and as the syringe is being pulled backward.
Spring-biased aspiration biopsy devices have been previously described by Lee U.S. Pat. No. 4,664,128, Hut U.S. Pat. No. 5,159,933 and DeSantis et al. U.S. Pat. No. 5,971,939 A. These devices have a variety of disadvantages based on the complicated grips, guides, and holders that encase the syringe and therefore introduce difficulty in retrieving the specimen if it is suctioned into the syringe. Indeed, the guides and holders described in Hut U.S. Pat. No. 5,159,933 and DeSantis et al. U.S. Pat. No. 5,971,939 A are in place to prevent overpressure from suctioning the tissue sample into the syringe.
Therefore, it would be desirable to provide an aspiration biopsy device that overcomes the aforementioned and other disadvantages.